A conventional wrench used on piping system is shown in FIG. 1 and an inherent shortcoming is that the jaws of the conventional wrench are wide and thick and the pipes are located very close to each other so that when rotating the wrench the jaws are blocked by the pipes around the object. FIG. 2 shows a conventional box end wrench that has thinner ring portion so that the wrench is convenient to rotate among the pipes. Nevertheless, the conventional wrench has to be disengaged from the object after it is rotated an angle which is limited especially when the space between the pipes is narrow. The frequent disengagement and engagement of the wrench and the object take a lot of time and reduce the efficiency of the work.
Other disclosed references known to the applicant are U.S. Pat. No. 2,401,128, U.S. Pat. No. 2,699,082, U.S. Pat. No. 6,382,051, U.S. Pat. No. 6,651,533, and U.S. Pat. No. 6,408,722.
The present invention intends to provide a ratchet pipe wrench wherein a C-shaped positioning ring is engaged with the head and secures the C-shaped engaging member in the head.